What are the structural features of ticks? - briefly
Ticks have a dorsoventrally flattened body composed of a prosoma and an idiosoma, covered by a sclerotized cuticle, and a capitulum bearing chelicerae, a hypostome, and palps for feeding. They possess four pairs of legs with sensory receptors that detect host cues, the first pair developing after engorgement.
What are the structural features of ticks? - in detail
Ticks are arachnids with a body divided into two main regions: the anterior capitulum and the posterior idiosoma. The capitulum houses the feeding apparatus, while the idiosoma contains the majority of internal organs and the protective exoskeleton.
The feeding apparatus consists of three paired structures:
- Chelicerae: short, blade‑like components that cut the host’s skin.
- Palps: sensory appendages that locate the feeding site.
- Hypostome: a barbed, tube‑like organ that anchors the tick and channels blood into the mouth.
The idiosoma is covered by a hardened dorsal plate (scutum) in males and partially in females; the remaining dorsal surface is a flexible cuticle that expands during engorgement. Ventral sclerotized plates (coxae) protect the leg bases. Six legs, each with seven segments, emerge from the coxae and provide locomotion and host detection.
Sensory perception relies chiefly on Haller’s organ, located on the first pair of legs. This organ integrates temperature, carbon‑dioxide, and odor cues to locate hosts.
Internal organization includes:
- Digestive tract: foregut (esophagus), midgut (midsection with cells specialized for blood digestion), and hindgut (Malpighian tubules for waste excretion).
- Reproductive system: paired ovaries and a single oviduct in females; paired testes and accessory glands in males.
- Nervous system: a ventral nerve cord with segmental ganglia, a synganglion (central brain) situated in the idiosoma, and peripheral nerves innervating the legs and mouthparts.
- Respiratory system: a network of tracheae delivering oxygen directly to tissues; no lungs are present.
- Hemocoel: a primary body cavity that circulates hemolymph, providing nutrient transport and immune functions.
These structural elements enable ticks to locate hosts, attach securely, ingest large blood meals, and reproduce efficiently, distinguishing them from other arachnids.